Marking a major milestone, Centrus Energy—a firm under contract with the U.S. Department of Energy (DOE) to demonstrate production of high-assay low-enriched uranium (HALEU) with domestic technology—on Feb. 9 said it completed construction and initial testing of its advanced uranium enrichment centrifuge cascade as well as most of its associated support systems.

Once the company completes the remaining works related to support systems at its facility leased from the DOE in Piketon, Ohio, it will seek the Nuclear Regulatory Commission’s (NRC’s) green light to demonstrate HALEU, the company said. If granted, the facility “will be the first new U.S.-owned, U.S.-technology enrichment plant to begin production in 70 years,” it noted. 

An Urgency for HALEU Supply

The first-of-a-kind demonstration has been delayed, but eagerly awaited, given its implications for alleviating—even if moderately—supplies of HALEU, a form of uranium-235 fuel enriched to 20%. Experts note that because HALEU is enriched higher than the 4% to 5% level typically used in existing reactors, it may provide more power per volume than conventional reactors, and its efficiency allows for smaller plant sizes. The fuel type also promises longer core life and a higher burn-up rate of nuclear waste. Many advanced nuclear reactor designs, including nine of the 10 designs awarded under the DOE’s Advanced Reactor Demonstration Program (ARDP), require HALEU. But currently, HALEU is available from only two sources: limited amounts from the DOE via down-blending of existing stockpiles of material and from commercial supplies via TENEX, a nuclear fuel company owned by Russian state-owned company Rosatom. 

When Centrus’s cascade of 16 AC100M centrifuges is up and running as planned by Dec. 31, 2023, it will demonstrate the production of 20 kilograms (kg) of 19.75% enriched HALEU, as required by a $150 million “definitized contract” the DOE awarded the company in November 2022. The contract spans two phases through 2024. Under Phase 2, Centrus plans to continue production for a full year at an annual production rate of 900 kg of HALEU. The DOE will own the HALEU produced from the demonstration cascade.

Centrus will be compensated on a cost-plus-incentive-fee basis, with an expected [Phase 2] contract value of approximately $90 million, subject to appropriations,” the company noted in November. “The contract also gives the Department options to pay for up to nine additional years of production from the cascade beyond the base contract; those options are at the Department’s sole discretion and subject to the availability of Congressional appropriations.”

Centrus Energy’s original AC100 machine was developed with support from the Department of Energy and later refined by Centrus to the current AC100M machine under contract with Oak Ridge National Laboratory. Centrus Energy will demonstrate 16 of its centrifuges at its enrichment facility in Piketon, Ohio. The machines will be used to enrich uranium hexafluoride gas to produce HALEU by December 2023 to support advanced reactor fuel qualification testing and reactor demonstration projects. Courtesy: Centrus

A Uniquely American Centrifuge Cascade

Centrus’s pioneering cascade uses gas centrifuge machines, which feed uranium hexafluoride (UF6)—heated to a gaseous state—into a rotor inside the centrifuge machine. A rotor spinning at high speed inside a steel casing uses centrifugal force to concentrate the heavier U-238 isotopes at the outer wall of the rotor and the lighter U-235 isotopes toward the rotor center. The streams are then fed to the next machines in a “cascade” to achieve the desired level of enrichment. Centrus will use a 4.95% LEU feed material for its planned HALEU 16 AC100M-centrifuge cascade. It suggests roughly 85% of the separative work units (SWU)—a measure of enrichment needed to produce HALEU—is already contained in the LEU feed material. 

Construction of the cascade began in 2019 under a three-year, $115 million, cost-shared contract with the DOE. While the DOE modified the contract several times to increase the total contract funding to $158.9 million, it later extended the period of performance to November 2022. Owing to COVID-related supply chain delays that hampered the delivery of HALEU storage cylinders, the DOE ultimately elected to move the operational portion of the demonstration to a new, competitively awarded contract, which Centrus was awarded in November.

Next Steps with a Bigger Milestone Expected at the End of 2023

Now that construction and initial testing of the cascade and its supporting systems are complete, Centrus plans to finish construction of the remaining support systems, including a fissile materials storage area, so that the HALEU produced for the Department can be stored onsite.

Centrus is also awaiting “complete final operational readiness reviews” with the NRC, which are required by a license the regulatory body awarded Centrus for the enrichment facility in June 2021. Centrus already holds an existing NRC license to produce fuel enriched up to 10% at the Piketon facility, where Centrus (then known as U.S. Enrichment Corp. before a post-bankruptcy rebrand) successfully demonstrated its advanced U.S. gas centrifuge uranium enrichment technology in 2013 as part of a three-year DOE project that ended in 2016. 

Beyond its operations contract with the DOE, Centrus says it is “investigating the possibility to scale up the Piketon facility with additional centrifuge cascades for expanded HALEU production.” That, however, will require “sufficient funding” and securing offtake contracts, the company acknowledges.

The opportunity is lucrative, Centrus suggested. “A full-scale HALEU cascade, consisting of 120 individual centrifuge machines, with a combined capacity of approximately 6,000 kilograms of HALEU per year (6 MTU/year), could be brought online within about 42 months of securing the funding to do so,” the company noted on Thursday. “Centrus has the capability to add an additional cascade every six months after that. Such an expansion would mobilize hundreds of union workers in Ohio to build and operate the plant and support thousands of direct and indirect jobs across a manufacturing supply chain that is 100 percent domestic and will be capable of meeting U.S. national security requirements.”

For now, however, Centrus is celebrating the milestone of completing the construction of its cascade. “This is a major milestone for Centrus, for the advanced nuclear sector, and for the vital effort to restore America’s domestic uranium enrichment capability,” noted Centrus Energy President and CEO Daniel B. Poneman. “We are strongly committed to pioneering production of HALEU to support the deployment of U.S. advanced reactor designs around the world. Our goal is to scale up this facility to meet the full range of commercial, government, and national security requirements for uranium enrichment, including Low-Enriched Uranium for existing reactors and HALEU for advanced reactors.”

Sonal Patel is a POWER senior associate editor (@sonalcpatel@POWERmagazine).